Methods are known in the art for glass manufacturing for preheating glass batch wherein glass-forming, batch ingredients are compacted into agglomerates and then are dried and heated in a chamber by a direct contact with flue gases from a glass melting furnace so as to produce free-flowing agglomerates which are then conveyed and discharged to the glass melting furnace. These agglomerates are composite, integral, self-supporting masses consisting essentially of all the substantial batch materials and may take the form of balls, extrusions, discs, briquettes, and pellets. The agglomerates are discharged to a vertical bed contained within a chamber and furnace flue gases pass, in direct contact with and countercurrently to, downwardly moving pellets of the bed to preheat them.
Particle-particle heat exchange between granular food products and spherical metal balls of different temperatures also are known in the art for heating the food products. The food products and metal balls are allowed to exchange heat in a rotating drum. This method allows the exchange of large quantities of heat economically and uniformly and without contamination from residues of the heat transfer medium.